Certain methods and equipment of this type are believed to be conventional. Seat heating historically originated from the idea of making passengers feel more comfortable even in open vehicles. A further condition arose from the idea of creating seat heating for the purpose of bridging the heating gap due to the heating-up time of the heating system which is sluggish apart from this. Vehicle seat heating may be a conventional feature intended to enhance seating comfort. Beyond that, however, there are also measures arising from the fact that motor vehicles are operated in all seasons in many climatic zones.
During the summer months motor vehicles are usually air-conditioned, so as to have a bearable climate in the passenger compartment. Thus, proceeding from this, it is believed to be conventional that vehicle seats may be designed not only to be heatable but also air conditioned.
While driving during the summer months, one may encounter situations in which weather conditions and temperatures lead to an increased development of perspiration. In motor vehicles, this may lead to the effect of the so-called wet back, e.g., on longer trips. In relation to this, it is believed to be conventional that heat vehicle seats may not only be heated as discussed above, but also ventilated. On the one hand, it may be important to carry off the dampness between passenger and vehicle seat, and on the other hand, to achieve a comfortable vehicle seat temperature.
German Published Patent Application No. 197 03 516 describes a vehicle seat which is provided with ventilation equipment for aerating the seat cushion, as well as a heating device for heating the cushion. In order to ensure great seat climate comfort, which, on the one hand, excludes perspiring and, on the other hand, excludes undercooling or excessive cooling of the user of the seat, a control device is provided which is connected on its input side to a temperature sensor positioned in the seat, and on its output side to the electrical switching circuits of the ventilation equipment and the heating equipment. In this manner, then, seat cooling and seat heating are fully and automatically regulated.
PCT International Published Patent Application No. WO 96/25301 describes a climate seat in which the inner side of the seat contact surface allows passage of conditioned air by an air conditioning device. An electrical heating element is arranged in the vicinity of the inner side of the seat contact surface, for heating the seat contact surface. A temperature sensing arrangement detects the temperature in the area of the seat contact surface. In order to achieve fast setting of the seat temperature to any given desired temperature, independent of the surrounding conditions, regulating equipment is provided, which is in contact with both the air conditioning equipment and the electrical heating element, and which regulates these in correspondence to a predefined temperature setpoint value as a function of the temperature measured by the temperature sensor equipment. Here too, no influence by the passenger on the automatic operation is possible.
European Published Patent Application No. 0 809 576 describes a climate seat, which carries out the full air conditioning in automatically regulated fashion.
Further implementations of seat air conditioning are described, as, for example, in PCT International Published Patent Application No. WO 98/55340, in which a seat air conditioning device has an air-permeable foundation arranged under a seat surface, and a heating element positioned in the foundation or between the seat surface and the foundation. The foundation and the heating element are formed mat-like, and are essentially oriented parallel to each other, and approximately of the same size with respect to surface extension. In the final analysis, the air permeability here creates the air conditioning or rather, gives access to the air flow.
German Published Patent Application No. 197 52 135 describes a method for temperature-independent regulation of the heat flow of a seat heating device, having a sensor element for temperature recording, and after switching on the seat heating device, the sensor registering the temperature, as a function of the difference of the sensor temperature from a comparison value, the heating phase duration is determined, and subsequently a heating phase is switched on for this duration. This relates for the most part to heating the seat, but ignores completely the aspect of full air conditioning and thus also of ventilation and possibly cooling.
Thus an overall disadvantage is believed to be created, in that the subjective feel of the person on the seat remains completely ignored, in the case of the arrangements mentioned above. Influence of the direct kind is avoided, and instead, a complete temperature-regulated guidance of the system is provided. However, it remains worth considering whether uncontrolled cooling, which ignores the subjective feel of the person in question, may lead to health consequences or even damage to health. Seen from that point of view, systems which are regulated exclusively in fully automatic fashion, even if temperature-regulated, represent an insufficient arrangement.